Many semi-automatic and automatic rifles utilize a gas-driven reloading system. These systems are often tuned by the rifle manufacturer for optimal performance of the firearm. However, the addition of an accessory (e.g., a suppressor) or the wear of components due to usage alters the firing characteristics of the firearm.
To compensate for such changes, adjustable gas regulators were introduced that allow for the metering (i.e., increasing or decreasing) of the gas flow. The majority of adjustable gas regulators use a screw or piston of some type to partially obstruct a round gas hole in the gas block and gas tube of the firearm/rifle, such as an AR-15. The flaw in this design is that as the screw is turned in and begins to obstruct the gas flow, it has little effect and that effect gets more progressive as the screw approaches the apex/center of the gas hole, and then progressively less as the screw advances into the back side of the hole. This causes inconsistent gas metering as one turn or one click has different effect from the previous adjustment and is unpredictable. Additionally, the gasses on some designs cause the screw to work its way out, and the tip of the screw may be eroded by the flow of hot gasses during operation, or, fouling of the threads of the screw with carbon from the burning gasses and gun powder residue.